This invention relates to a core capping apparatus for fixing a conforming sleeve within a tubular member, and more particularly to a capping head for securely fixing an end cap within the bore of a tubular fiber core.
When bulk paper products such as blank newsprint sheet are manufactured, they are typically wound onto elongate tubular fiber cores forming large paper rolls for storage and transport. The end user of these bulk paper products customarily mounts these paper rolls upon machines having rotating chucks which grip the ends of the roll and spin the roll to dispense the paper therefrom. In some applications, such as newspaper printing, the paper is stripped from the spinning roll by high-speed printing presses which impart to the spinning paper roll considerable rotary inertia. When the high-speed printer is stopped, the rapidly spinning roll must be simultaneously braked to prevent over-spin of the roll and resultant unwinding of unused paper.
The fiber cores used for these rolls which do not have metal caps on their ends usually have serrated or slotted ends, and the chucks for rotatably mounting these types of cores have mating keys or serrations to enable them to positively engage the cores. Since the relatively soft fiber cores are forcefully interfaced with hard metal chucks, and considerable forces are transmitted through this interface, applying braking force to the roll through the chucks often damages the fiber cores, preventing re-use of the cores. Misalignment of the key and slot or the serrations during mounting of the cores can also damage the cores. For these reasons some fiber cores are being provided with metal caps which are fixed within the ends of the core, such caps usually comprising an internal conforming sleeve and an exterior annular flange, the flange lying flush on the flat end planes of the typically elongate cylindrical core. These capped cores mount on machines having expandable chucks which are inserted into the conforming metal sleeve portion of the caps, which in turn have been previously fixed within the extreme ends of the cores. The chucks expand to securely grip the sleeve portions of the caps and acceleration or braking force is applied to the core through the interface of the metal caps and chucks. This method of mounting the fiber cores prevents damage to the cores and enables them to be re-used many times. However, because of the considerable force applied to these caps in braking the spinning rolls of paper, it is essential that the caps be securely fixed within the ends of the core. For example, Japanese printers require that the cap be fixed within the core by at least six punched protrusions.
Applicant is aware of a prior art core capping apparatus manufactured by Berlin Foundry of New Hampshire comprising a floating-type capping head having four rampactuated pivoting head segments, each head segment having an associated crimper and punch and a spring loaded shield to cover the punch. An associated, axially sliding ramp forces each head segment to swing radially outward in an arcuate path, the crimper on the spring-loaded shield contacting the inner sleeve of the cap and forcing the shield to retract so that the punch extends through a hole in the shield and the punch and crimper deflect portions of the conforming sleeve to deformably engage the tubular core.
This type of core capping apparatus has several major problems and limitations: each crimper and punch is mounted on a separate head segment, thereby effectively limiting the number of punches by the growing complexity entailed in increasing the number of head segments; the crimper and punch engage the sleeve portion of the cap in an arcuate path, resulting in side-loading stresses on the punch, crimper and head segment; each head segment pivots around a single pin which tends to break frequently due to the considerable applied forces; the punches and the shield retaining screw also tend to break frequently due to the applied forces; the head segments can become misaligned from their respective actuating ramps; and finally, because there are many moving parts having metal-to-metal contact, and because these parts cannot be adequately lubricated due to the open floating nature of the head, the apparatus exhibits excessive wear. In addition, the four punches provided by this type of head may not provide a sufficiently strong interface between the core and the cap to handle high speed braking.